Syringe

ABSTRACT

A single use syringe in which the needle is rendered inoperative by retraction after injection has taken place.

BACKGROUND OF THE INVENTION

It has been very well established that many diseases are spread bypersons who share intravenous needles. Persons who share needles in thisway are usually drug addicts and this brings about the spreading of suchdiseases as AIDS or Hepatitis. It has been suggested, therefore, thatthe disease spread can be reduced by making clean needles available todrug users. However, there is no way of controlling the multiple use ofneedles when this is done. In addition, there is a rising concern amongmedical personnel who are involved in hypodermic needle use, either inconnection with injection of medicines or in taking blood samples. Aneedle which has been used for this purpose, if contaminated with thedisease, is a very dangerous instrumentality; there is documentedevidence that nurses and doctors scratched by accident with such needleshave had disease and even death from the contact. These problems havebeen obviated in a novel manner by the present invention.

It is therefore, an outstanding object of the invention to provide asyringe that includes a mechanism that would allow a only one loadinginto the syringe cylinder of any particular drug or fluid that is to beinjected.

Another object of this invention is the provision of a hypodermicsyringe having a mechanism that causes the plunger and needle assemblyto become an integral assembly, thus preventing a second loading of thedrug or fluid, because the mechanism stops the pump suction ability ofthe entire product.

A further object of the present invention is the provision of ahypodermic syringe that will assist in the national and internationalefforts to inhibit the spread of the AIDS virus among those intravenousdrug users who now tend to share needles with fellow drug users.

It is another object of the instant invention to provide a hypodermicneedle that is capable of only one use, thus preventing the spread ofany one of a number of diseases brought about by the sharing ofcontaminated needles.

A still further object of the invention is the provision of a hypodermicneedle that, after a first use, causes the needle to be retracted intothe cylinder, thus providing for safer disposal and for relief of thesignificant level of fear among health car workers who must daily workwith hypodermic syringes.

It is a further object of the invention to provide a hypodermic syringewhich is simple in construction, which can be manufactured fromrelatively inexpensive materials, and which is capable of use andstorage with a minimum of care.

With these and other objects in view, as will be apparent to thoseskilled in the art, the invention resides in the combination of partsset forth in the specification and covered by the claims appendedhereto.

SUMMARY OF THE INVENTION

In general, the invention consists of a hypodermic syringe having anelongated cylinder with a first bore extending into one end andterminating in a closure at the other en. A second bore extends throughthe closure coaxially of the first bore. A plunger lies slidably in thefirst bore and has a section at the inner end fitting tightly in thebore while having a section at the outer end extending from the plungerfor use in sliding the plunger to and from in the bore. A needleassembly is provided, having a main body that sits snugly and slidablyin the second bore and having a flange that fits snugly and slidably inthe first bore. A detent means is associated with the needle assembly tolock the needle assembly to the plunger when the plunger has beeninitially completely depressed, so that the needle assembly is caused toretract into the cylinder when the plunger is subsequently retracted.

More specifically, the plunger has a coaxial passage extending entirelythrough it and the needle assembly has a rod that fits slidably in thepassage. The detent means consists of cooperating parts of the plungerand the free end of the rod. The free end of the rod is provided withspaced, parallel fingers, each of which is provided with anoutwardly-extending abutment, while the passage in the plunger isprovided with a shoulder that cooperate with the finger abutments as theplunger approaches the completely depressed condition and retractionbegins.

BRIEF DESCRIPTION OF THE DRAWINGS

The character of the invention, however, may be best understood byreference to one of its structural forms, as illustrated by theaccompanying drawings, in which:

FIG. 1 is a perspective view of a hypodermic syringe incorporating theprinciples of the present invention, and

FIG. 2 is a vertical sectional view of the syringe taken along the lineII--II of FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring first to FIG. 1 wherein are best shown the general features ofthe invention, it can be seen that the hypodermic syringe, indicatedgenerally by the reference numeral 10, is shown as having an elongatedcylinder 11 having a closure 14 at one end. A plunger 16 extends intothe cylinder and a needle assembly 19 extends through a bore 15 throughthe closure 14 and carries a hypodermic needle 20. The plunger 16 isprovided with a section 18 in the form of a flange permitting theplunger to be withdrawn, retracted, or depressed.

Referring now to FIG. 2, it can be seen that the cylinder 11 is providedwith a first bore 12 which extends into one end 13 of the cylinder. Thefirst bore terminates at the other end at the enclosure 14 and a secondbore 15 extends through the closure coaxially of the first bore 12.

The plunger 16 lies and extends through the first bore 12 and has asection 17 fitting tightly in the bore; this section carries a rubberO-ring or seal 30. As has been stated above, a section 18 in the form ofa flange at the other end of the plunger is provided for use in manuallysliding the plunger to and from in the bore 12.

The needle assembly 19 includes a main body 21 which fits snugly andslidably in the second bore 15. The needle assembly is also providedwith a flange 22 that fits snugly and slidably in the first bore 12.

Detent means 23 is associated with the needle assembly to lock theneedle assembly to the plunger when the plunger has been initiallycompletely depressed, so that the needle assembly is caused to retractinto the cylinder when the plunger is subsequently retracted.

As is evident in FIG. 2, the plunger 16 has a coaxial passage 24 in theform of a bore which extends entirely through the plunger and whoseouter end is closed by a plug 30 which is cemented in place. The needleassembly 19 is provided with a rod 25 which fits slidably in thepassage. The detent means 23 consists of cooperating parts of theplunger and the free end of the rod 25. More specifically, the free endof the rod 25 is provided with a pair of spaced parallel fingers 26 eachof which is provided an outwardly-extending abutment 27. The passage 24in the plunger is provided with a shoulder 28 formed by a counterbore31. This shoulder cooperates with the finger abutments 27 as the plungerreaches the completely depressed condition and retraction begins.

A sleeve 29 is slidable in the counterbore 31 and is provided tomaintain the abutments 27 out of engagement with the shoulder 28 duringan initial filling retraction of the plunger. This sleeve becomesinoperative during the depression movement of the plunger, so that, whenthe plunger is subsequently retracted, the abutments 27 engage theshoulder 28 and the needle assembly 19 is drawn entirely into thecylinder along with the needle 20.

The operation and the advantages of the present invention will now bereadily understood in view of the above description. In order to fillthe hypodermic syringe 10 with the fluid which is to be intravenouslyinjected, the cylinder 11 is held in one hand and the other hand is usedin conjunction with the section 18 of the plunger to pull the plungeroutwardly of the first bore 12. This causes a vacuum to develop betweenthe seal 30 and the flange 22 of the needle assembly 19. As the plungeris further withdrawn, the fluid flows into and fills the cylinder; whenthe plunger reaches its extreme position outwardly, the syringe is readyfor the injection of the fluid. It should be noted that, as the plungeris retracted, there is no engagement between the abutments 27 on the rod25 of the needle assembly with the shoulder 28, because of the presenceof the sleeve 29 which, because of the friction between the abutmentsand the inner surface of the sleeve, causes the sleeve to be forceddownwardly against the shoulder 28. After the needle 20 has beenintroduced into the vein of the person being treated, the plunger 16 isthen pressed inwardly causing it to move into the first bore 12 andexpress the fluid. The friction between the abutments 27 of the rod 25at that time and the inner surface of the sleeve 29 are such as to pressthe sleeve 29 along the counter bore 31. By the time the plunger reachesthe position in which most of the fluid has been introduced into thepatient, the sleeve 29 lies well away from the shoulders 28. Then, whenone attempts to retract the plunger 16 for a reload or deliberately inorder to render the syringe inoperative, the fingers 26 snap outwardlyand the shoulders on the abutments 27 engage the shoulder 28 on theplunger. Therefore, as the plunger proceeds outwardly of the first bore12, the needle assembly is carried with it. It moves smoothly throughthe first bore along with the plunger and eventually the needle 20 liesentirely inside of the cylinder.

It can be seen, then, that, when the needle is used in this way, twothings happen. If the medical person wishes to render the needleinaccessible, so that it cannot accidentally scratch a nurse or doctor,the plunger is pulled completely out, causing the needle to retractinside the cylinder. In the finished condition, of course, the sleeve 29is removed away from the fingers 26 and lies nearer to the entrance ofthe counterbore 31. If one pushes the plunger 16 inwardly again, theplunger simply causes the needle assembly to slide back out again, butany attempt to retract the plunger to introduce fluid into the cylinderwill simply cause the needle to retract again. In other words, in thecase of medical personnel, they will probably discard the package withthe needle assembly entirely inside the cylinder. If one attempts toabuse the situation by presenting the needle back into operativecondition again, the retraction of the plunger will not cause fluid toenter syringe for use by a drug addict for instance, but will only causerepeated retraction of the needle assembly to the inside of thecylinder. In other words, the syringe is rendered useless in eithersituation.

The present invention, when incorporated into a hypodermic syringe, willallow only a single loading into the syringe cylinder of any particulardrug or fluid that is to be injected. After injection, the mechanismcauses the plunger and the needle assembly to become an integralassembly, thus preventing a second loading of a drug or fluid, since themechanism stops the pump suction ability of the entire product. Thevalue of this invention is such that it will assist in the national andinternational efforts to inhibit the spread of the AIDS virus amongintravenous drug users who now tend to share needles with fellow drugusers. The spread of any one of a number of diseases, such as AIDS orhepatitis is brought about by this sharing of a contaminated needle. Ithas been determined that in the calendar year 1987, an estimated12,000-15,000 health care workers in the United States contracted theHepatitis-B virus by accidentally sticking themselves with contaminatedneedles. Of this 12,000-15,000 estimate, 200-300 resulted in fatality.

The present invention, in addition to preventing a second injection,also allows the needle to be retracted back up and into the cylinder,thus allowing for considerably safer disposal and relief of thesignificant level of fear amongst health care workers who must dailywork with hypodermic syringes. It has been noticed that the widespreadfear of this contamination has been evidenced by the number of nurses,blood sample technicians, and dentists who are now leaving or seriouslyrestricting their professions.

The invention having thus been described, what is claimed as new anddesired to secure by Letters Patent is:
 1. Syringe comprising:(a) anelongated cylinder having a first bore extending into one end andterminating in a closure at the other end, a second bore extendingthrough the closure coaxially of the first bore, (b) a plunger extendsthrough the first bore and has a section fitting tightly in the bore,while having a section extending from the said first end for use insliding the plunger to and from in the bore, (c) a needle assemblyhaving a main body that fits snugly and slidably in the second bore andhas a flange that fits snugly and slidably in the first bore, theplunger having a passage extending therethrough and the needle assemblyhaving a rod fitting slidably in the passage, and (d) detent means isassociated with the needle assembly to lock the needle assembly to theplunger when the plunger has been initially completely depressed, sothat the needle assembly is caused to retract into the cylinder when theplunger is subsequently retracted.
 2. Syringe as recited in claim 1,wherein the plunger has a coaxial passage extending entirely through itand the needle assembly has a rod that fits slidably in the passage. 3.Syringe as recited in claim 2, wherein the detent means consists ofcooperating parts of the plunger and the free end of the rod.
 4. Syringeas recited in claim 3, wherein the said free end of the rod is providedwith a pair of spaced, parallel fingers each of which is provided withan outwardly-extending abutment, and wherein the passage in the plungerhas a counterbore defining a shoulder that cooperate with the fingerabutments as the plunger approaches the completely depressed conditionand retraction begins.
 5. Syringe as recited in claim 4, wherein asleeve is provided slidable to counterbore to maintain the abutments outof engagement with the shoulder during an initial filling retraction ofthe plunger, which sleeve becomes inoperative during the depressionmovement of the plunger, so that, when the plunger subsequently isretracted, the abutments engage the shoulder and the needle assembly isdrawn entirely into the cylinder.
 6. Syringe comprising:(a) an elongatedcylinder having a first bore extending into one end and terminating in aclosure at the other end, a second bore extending through the closurecoaxially of the first bore, (b) a plunger extends through the firstbore and has a section fitting tightly in the bore, while having asection extending from the said first end for use in sliding the plungerto and from in the bore, (c) a needle assembly having a main body thatfits snugly and slidably in the second bore and has a flange that fitssnugly and slidably in the first bore, the plunger having a passageextending therethrough and the needle assembly having a rod fittingslidable in the passage, (d) detent means is associated with the needleassembly to lock the needle assembly to the plunger when the plunger hasbeen initially completely depressed, so that the needle assembly iscaused to retract into the cylinder when the plunger is oncesubsequently retracted, and (e) means causing the needle assembly toremain in the cylinder when the plunger is moved in and out after it hasonce been so retracted.